This invention relates to a self-centering gate of the type which includes spring biasing means for biasing the gate to a central closed position from open positions on either side of the closed position.
Spring mounted gates fo this type are well known and are used particularly for retaining livestock within an area while allowing vehicles to move in and out of the area without halting to open and close the gate. Thus the gate can freely pivot open from its normal closed position merely by engaging the vehicle so the vehicle pushes the gate open and then the gate springs closed as the vehicle passes through.
In many cases gates of this type comprise an elongate bar which is electrified so that it can be a relatively lightweight structure and yet use the electric shock system to retain the animals within the restricted area.
One problem which arises with spring mounted devices of this type is that the amount of biasing force increases as the gate is pivoted from the closed position toward a fully open position so that by the time it reaches the fully open position there is significant force against the vehicle which can cause scratching or other damage. If of course the spring force is reduced so that at the open position it is an acceptable force then the spring force around the closed position is very weak and does not properly hold the gate in the closed position. A yet further problem which can arise in devices of this type is that it is desirable that they be extendable to cover various different lengths of open area and yet communicate the electric shock system along the full length of the gate.
According to the first aspect of the invention, therefore, is provided a self-centering stock-proof gate comprising a gate structure for extending across an area to be gated, a support structure including hinge means for supporting the gate structure for pivotal movement about a vertical axis at one side of the area such that the gate structure is movable from a closed position extending across a set area to each of two open positions each substantially at right angles to the closed positions, first and second spring coupling means each for biasing said gate structure from a respective one of said open positions to said closed position and means coupling said spring coupling means from said gate structure to said suport structure and including first and second slide coupling means each mounted on said support structure so as to extend the front said axis forwardly and outwardly to a respective side of said axis, each said slide coupling means being arranged to receive an end of said respective spring coupling means for movement of said end from a position outwardly of said axis to position adjacent to said axis, the orientation of the slide coupling means and the connection between the spring coupling means from the slide coupling means to the gate structure being arranged such that in the closed position said ends slides to said outward position and as said gate moves toward a respective one of the open positions, the end slides toward said adjacent position.
According to the second aspect of the invention is provided a self-centering stock proof gate comprising a gate structure for extending across an area to be gated, a support structuring including hinge means for supporting the gate structure for pivotal movement about a vertical axis at one side of the area such that the gate structure is movable from a closed position extending across to the area to each of two open positions each substantially right angles to the closed angles, first and second spring coupling means for biasing said gate structure from a respective one of said open positions to said closed position, said gate structure comprising an elongate tube member extending substantially horizontally from said hinge means to an open end of said tube member remote from said hinge means and an extension piece mounted within said tube member and slideable therein from a position in which it is substantially wholly retracted therein to an extended position therefrom, said extension piece comprising a fibre reinforced plastic rod having an electrically conductive wire embedded in the surface thereof.
It is one advantage of the invention, therefore, that the spring force is reduced as the gate moves to the open position by the slide coupling which allows the pull on the gate to be moved from a position outwardly of the axis to a position closer to the axis so that the mechanical advantage of the spring reduces while the linear force increases.
Preferably, each of the slide coupling comprises a pin which extends outwardly from the support structure with the pin also extending slightly upwardly while extending forwardly and outwardly to the side. This ensures that the connecting chain extending from the pin to the gate as it slides downwardly along the pin in the open position of the gate passes underneath the other of the pins while the chain to that other pin merely becomes loose.
With the foregoing in view, and other advantages as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, the invention is herein described by reference to the accompanying drawings forming a part hereof, which includes a description of the best mode known to the applicant and of the preferred typical embodiment of the principles of the present invention, in which: